title: No clinical difference between large metal-on-metal total hip arthroplasty and 28-mm-head total hip arthroplasty?
abstract: OBJECTIVE
  We aimed to test the claim of greater range of motion (ROM) with large femoral head metal-on-metal total hip arthroplasty.
  
  
  METHODS
  We compared 28-mm metal-on-polyethylene (MP) total hip arthroplasty with large femoral head metal-on-metal (MM) total hip arthroplasty in a randomised clinical trial. ROM one year postoperatively was determined in 50 patients. Mean head sizes were 28 mm (MP) and 48 mm (MM).
  
  
  RESULTS
  After one year, the large head MM group showed greater improvement in internal rotation (14 degrees) than the 28 mm group (seven degrees).There were no significant differences in the absolute values of postoperative internal rotation, external rotation, flexion, extension, abduction and abduction.
  
  
  CONCLUSIONS
  Absolute postoperative range of motion did not differ between the two groups. The improvement in internal rotation was greater after large femoral head metal-on-metal total hip arthroplasty. It is however questionable whether this difference is clinically relevant.
authors.affiliation: Department of Orthopaedic Surgery, Martini Hospital, Groningen, The Netherlands. wpzijlstra@hotmail.com
authors.forename: Wierd P
authors.initials: WP
authors.lastname: Zijlstra
authors.forename: Inge
authors.initials: I
authors.lastname: van den Akker-Scheek
authors.forename: Mark J M
authors.initials: MJ
authors.lastname: Zee
authors.forename: Jos J A M
authors.initials: JJ
authors.lastname: van Raay
mesh_terms: D000368:Aged; D001168:Arthritis / Q000209:etiology / Q000601:surgery; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation / Q000379:methods*; D017760:Bone Malalignment; D005260:Female; D005270:Femur Head; D005271:Femur Head Necrosis / Q000601:surgery; D006304:Health Status; D025981:Hip Injuries / Q000150:complications / Q000601:surgery; D006621:Hip Joint / Q000503:physiopathology / Q000601:surgery*; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008670:Metals; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000601:surgery; D017063:Outcome Assessment, Health Care; D020959:Polyethylene; D011474:Prosthesis Design; D016059:Range of Motion, Articular; D020127:Recovery of Function; D016896:Treatment Outcome
chemical_list: D008670:Metals; D020959:Polyethylene